Real eigenstate targeted magnetic energy control method based on multi-mutual inductance ratio front-end detection and positioning

Abstract

The present invention relates to the field of wireless power transmission technology, and specifically discloses a real eigenstate targeted magnetic energy control method based on multi-mutual inductance ratio front-end detection and positioning. First, a voltage regulating circuit is added between a DC power supply and each inverter circuit, and then the mutual inductance ratio is calculated by obtaining two transmitting loop currents by exciting the system twice, and then the voltage regulating circuit is adjusted according to the mutual inductance ratio, and then the eigenfrequency of the system is determined by frequency scanning, so that the system can select the corresponding eigenfrequency for excitation according to the mutual inductance ratio and charging demand. This method does not require the front-end transmitting coil to communicate with the back-end receiving coil, the time for identifying the mutual inductance ratio is short, and the complex calculation process during the eigenstate frequency detection is eliminated, which greatly reduces the difficulty of identifying the eigenfrequency value and simplifies the complexity of the system. This method accurately controls the energy transmission mode of the targeted magnetic energy, which can not only ensure the transmission efficiency of the system, but also ensure the output power of the system.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless power transfer (WPT), and in particular to a real eigenstate targeted magnetic energy control method based on multi-mutual inductance ratio front-end detection and positioning. Background Art

[0002] Wireless power transfer (WPT) technology is an indispensable supporting technology for supporting unmanned operation and improving the endurance of equipment. Magnetic coupling wireless power transfer (MC-WPT) technology is the most mature and widely used WPT technology, and has gradually been applied to many fields such as consumer electronics, household appliances and electric vehicles. At present, most MC-WPT systems are for one-to-one wireless energy transmission, but due to the strong attenuation characteristics of magnetic energy, the transmission distance of a single transmitting coil is short and the energy transmission range is small.

[0003] The Multi-transmitter Wireless Power Transfer (Multi-transmitter WPT) system has multiple transmitting coils and one receiving coil, which has incomparable advantages over wireless power transmission with a single transmitting coil:

[0004] 1) The arrangement and combination of the positions of multiple transmitting coils are relatively flexible, and the positions of the transmitting coils can be designed according to the space requirements of the actual system.

[0005] 2) By increasing the number of transmitting coils, the range of wireless power transmission and the system output power can be greatly expanded.

[0006] 3) By precisely controlling the magnetic field of each transmitting coil, the transmission efficiency of the system can be improved.

[0007] Compared with the single transmitting coil WPT system, the multi-transmitting coil WPT system has the following disadvantages:

[0008] 1) The circuit structures of each transmitting coil are independent of each other, and the overall structure of the system is relatively complex.

[0009] 2) The improvement of the system's efficiency has no direct relationship with the number of transmitting coils. The lack of an effective magnetic energy control method will lead to greater magnetic leakage and reduced efficiency.

[0010] 3) The mutual inductances of the transmitting coils and receiving coils are often quite different, making it difficult to simply, quickly and accurately detect multiple mutual inductance parameters.

[0011] Multi-transmitter WPT technology has attracted much attention in recent years, but there is little research on the detection of multi-mutual inductance and magnetic energy control methods. At present, there are three main methods for multi-transmitter WPT mutual inductance detection:

[0012] 1) Based on the single-transmit mutual inductance identification, each transmitting coil is stimulated one by one, and the mutual inductance between each transmitting coil is extracted separately. Therefore, the detection of each mutual inductance requires a detection cycle. This method not only takes a long time to detect, but also has a more complicated detection procedure. In addition, depending on the specific method of single-transmit-single-receive mutual inductance detection used, additional circuits may be required, resulting in additional system losses and reduced system efficiency.

[0013] 2) Install a posture sensor at the receiving coil, and calculate the mutual inductance electrical parameters based on the position information of the receiving coil through communication between the front and back ends. The method of using a posture sensor to detect mutual inductance requires not only communication between the front-end transmitting coil and the back-end receiving coil, but also the actual mutual inductance value to be inferred based on the position information. This will not only increase the detection cost, but also greatly increase the complexity of the system in the actual WPT system.

[0014] 3) Based on the LCC-S topology, the voltage and current of each transmitting coil are detected to deduce the mutual inductance of each transmitting coil. However, this method is only applicable to systems under the specific LCC topology and is usually not applicable to commonly used topologies such as SS and PS. In addition, it has high requirements for the detection accuracy of the detection circuit.

[0015] The existing magnetic energy control method of multi-transmitter WPT is mainly based on the magnetic coupling resonant working mechanism, that is, the system operating frequency is fixed to the natural frequency of the coil. However, this working mechanism only analyzes the case where the operating frequency is the natural frequency of the coil. Under complex working conditions with changing loads and coupling, it is often difficult to take into account both the output power and transmission efficiency of the system.

[0016] In summary, although multi-transmitter WPT technology has received much attention in recent years, there is still little research on the detection of mutual inductance and the control of magnetic energy, and there is currently no good solution. The existing methods are difficult to achieve fast, accurate and multi-mutual inductance detection without relying on communication, and lack a suitable working mechanism that takes into account system transmission efficiency and meets high power output under complex working conditions. Summary of the invention

[0017] The present invention provides a real eigenstate targeted magnetic energy control method based on multi-mutual inductance ratio front-end detection and positioning, and solves the technical problem of how to simply, quickly and accurately control the targeted magnetic energy transmission mode to ensure both the transmission efficiency and the output power of the system.

[0018] In order to solve the above technical problems, the present invention provides a real eigenstate targeted magnetic energy control method based on multi-mutual inductance ratio front-end detection and positioning, comprising the steps of:

[0019] S1, DC power supply U at the transmitting end of the multi-transmitter wireless power transmission system dc A voltage regulating circuit is added between each inverter circuit; the transmitting end of the multi-transmitter wireless power transmission system includes a DC power supply U dc and n identical inverter circuits connected in parallel therewith, and n identical transmitting circuits connected one-to-one with the n inverter circuits;

[0020] S2, by controlling the corresponding voltage regulating circuit and inverter circuit, any two transmitting circuits are excited successively. When any transmitting circuit is excited, the remaining n-1 transmitting circuits that have not been excited and their inverter circuits form n-1 response circuits;

[0021] S3, measuring the currents of n-1 response loops corresponding to the two excitations, and calculating the mutual inductance ratios between the n transmitting coils and the receiving coils according to the measured currents;

[0022] S4, controlling the output voltage control signal ratio of n voltage regulating circuits to be the calculated mutual inductance ratio;

[0023] S5. Within the range of the starting frequency and the ending frequency, the excitation frequencies of the n inverter circuits are adjusted by increasing the set step size each time;

[0024] S6. Measure the phase difference of the input voltage and current of any transmitting circuit at each excitation frequency, and record the excitation frequencies from small to large with zero phase difference as the eigenfrequency f. 1 ,f 2 ,f 3 ;

[0025] S7, according to the system control requirements, the eigenfrequency f 1 or 2 or 3 The n inverter circuits are excited to perform wireless energy transmission for targeted magnetic energy control.

[0026] Furthermore, in step S3, the mutual inductance ratio between the n transmitting coils and the receiving coil is calculated according to the measured current as follows:

[0027] The current ratio of the n-1 transmitting loops that are not excited during the first excitation is set equal to the mutual inductance ratio between the n-1 transmitting loops and the receiving coil, and a first mutual inductance ratio current ratio constraint relationship is established;

[0028] The current ratio of the n-1 transmitting loops that are not excited during the second excitation is set equal to the mutual inductance ratio between the n-1 transmitting loops and the receiving coil, and a second mutual inductance ratio current ratio constraint relationship is established;

[0029] The first mutual inductance ratio-current ratio constraint relationship and the second mutual inductance ratio-current ratio constraint relationship are combined to solve the mutual inductance ratio between the current n transmitting loops and the receiving coil.

[0030] Furthermore, the step S7 is specifically as follows:

[0031] If the system control requirement is high-efficiency transmission, then f 2 Exciting n inverter circuits;

[0032] If the system control requirement is high power transmission, then f 1 or 3 n inverter circuits are excited.

[0033] Further, in step S4, the voltage regulating circuit adopts a Buck-Boost step-up / step-down chopper circuit, and the control signal of the voltage regulating circuit i is defined as δ i =t oni / t offi , t oni ,t off are the on-time and off-time of the switch tube of the voltage regulating circuit i, i=1,2,,…,n.

[0034] Further, steps S4 to S6 specifically include the steps of:

[0035] B1. Input the calculated mutual inductance ratio M between the transmitting coils 1s :…:M ns , M is Indicates the transmitting coil L i With receiving coil L s mutual induction between

[0036] B2. According to the mutual inductance ratio M 1s :…:M ns , control the switch tube S of the voltage regulating circuit 1, 2, ..., n 1 ,…,S n , the control signal is δ 1 :…:δ n =M 1s :…:M ns ;

[0037] B3, adjusting the excitation frequency of the inverter circuits 1, 2, ..., n to excite the system at the starting frequency;

[0038] B4. Measure the phase difference between the input voltage and current of any transmitting circuit;

[0039] B5. Judge the phase difference. If the phase difference is zero, record the excitation frequency at this time, from small to large, as f 1 ,f 2 ,f3 ; If the phase difference is not zero, determine whether the excitation frequency reaches the termination frequency. If the excitation frequency has not reached the termination frequency, increase the excitation frequency by the step size and return to step B4;

[0040] B6, output eigenfrequency f 1 ,f 2 ,f 3 .

[0041] Furthermore, the transmitting circuit i includes a transmitting coil L i And the primary side series compensation capacitor C i .

[0042] Furthermore, the receiving end of the multi-transmitter wireless power transmission system includes a receiving coil L s , Secondary side series compensation capacitor C s and the equivalent load resistance R L .

[0043] Further, in step S2, the excitation frequency for exciting any two transmitting loops is the natural frequency of the transmitting loop coils.

[0044] The real eigenstate targeted magnetic energy control method based on multi-mutual inductance ratio front-end detection and positioning provided by the present invention first adds a voltage regulating circuit between a DC power supply and each inverter circuit, then obtains two transmitting loop currents by exciting the system twice to calculate the mutual inductance ratio, further adjusts the voltage regulating circuit according to the mutual inductance ratio, and then determines the system's eigenfrequency (one fixed frequency and two floating frequencies) by frequency scanning, so that the system can select the corresponding eigenfrequency for excitation according to the mutual inductance ratio and charging demand. In the detection of multiple mutual inductance ratios and eigenfrequencies, this method does not require the front-end transmitting coil to communicate with the rear-end receiving coil, the time for identifying the mutual inductance ratio is short, and the complex calculation process during the eigenstate frequency detection is eliminated, which greatly reduces the difficulty of identifying the eigenfrequency value and simplifies the complexity of the system. According to the constraints of the real eigenstate working mechanism, multiple mutual inductance ratios and excitation current, this method accurately controls the energy transmission mode of the targeted magnetic energy, which can not only ensure the transmission efficiency of the system, but also ensure the output power of the system. The method can switch between floating frequency mode and fixed frequency mode. The floating frequency mode has a larger output power, and the fixed frequency mode has a higher transmission efficiency. The switching of the two modes enables the entire system to have a strong ability to cope with complex working conditions. The method excites each transmitting coil according to the coupling situation, reduces the leakage magnetic field of the transmitting coil, and improves the transmission efficiency of the system. The present invention can realize the identification of key system parameters and precise control of targeted magnetic energy in wireless charging applications with complex working conditions such as drones and unmanned ground vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1is a circuit structure diagram of a multi-transmitter wireless power transmission system provided by an embodiment of the present invention;

[0046] Figure 2 It is a circuit structure diagram of a transmitting end of a multi-transmitter wireless power transmission system after adding a voltage regulating circuit provided by an embodiment of the present invention;

[0047] Figure 3 The embodiment of the present invention provides a method for making the voltage regulating circuit and the inverter circuit equivalent to an AC voltage source. Figure 2 Equivalent circuit diagram of

[0048] Figure 4 is a diagram showing the relationship between the current vector of the transmitting coil and the current vector of the receiving end provided in an embodiment of the present invention;

[0049] Figure 5 is a mutual inductance ratio identification principle diagram provided by an embodiment of the present invention;

[0050] Figure 6 is an equivalent circuit diagram of multiple mutual inductance ratio identification provided by an embodiment of the present invention;

[0051] Figure 7 is a working state diagram of the switch tube of the inverter circuit 2 provided in an embodiment of the present invention;

[0052] Figure 8 is a mutual inductance ratio process principle diagram provided by an embodiment of the present invention;

[0053] Fig. 9 is a schematic diagram of the intrinsic frequency identification principle provided by an embodiment of the present invention;

[0054] Fig.10 is a flow chart of eigenfrequency identification provided by an embodiment of the present invention;

[0055] Fig.11 is an equivalent circuit diagram of eigenfrequency identification provided by an embodiment of the present invention;

[0056] Fig.12 is a current waveform diagram of the transmitting circuits 2 and 3 provided in an embodiment of the present invention;

[0057] Fig.13 is a current waveform diagram of the transmitting circuits 1 and 3 provided in an embodiment of the present invention;

[0058] Fig.14 is the excitation voltage of the transmitting circuit 1 provided in the embodiment of the present invention and current A graph showing the phase difference versus frequency.

[0059] Fig.15 is a relationship diagram of the output power of the system changing with the load under the real eigenstate working mechanism provided by an embodiment of the present invention;

[0060] Fig.16 is a graph showing the relationship between the transmission efficiency of the system and the load under the real eigenstate working mechanism provided by an embodiment of the present invention;

[0061] Fig.17 is a relationship diagram of the output power of the system under the real eigenstate working mechanism provided by an embodiment of the present invention as a function of the sum of the squares of the coupling coefficients;

[0062] Fig.18 It is a relationship diagram of the transmission efficiency of the system under the real eigenstate working mechanism provided by an embodiment of the present invention and the change of the sum of the squares of the coupling coefficients. DETAILED DESCRIPTION

[0063] The following specifically illustrates the implementation mode of the present invention in conjunction with the accompanying drawings. The embodiments are provided for illustrative purposes only and cannot be understood as limiting the present invention. The accompanying drawings are provided for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention.

[0064] The structure of the multi-transmitter wireless power transmission system is as follows: Figure 1 As shown, it includes a transmitting end and a receiving end. The transmitting end includes a DC power supply U dc (DC output current is I dc ) and n inverter circuits connected in parallel therewith (inverter circuit 1 to inverter circuit n, where inverter circuit i is composed of switch tube S i1 To S i4 and diode D i1 To D i4 The full-bridge inverter consists of i = 1, 2, ..., n, and the output voltage of the inverter circuit i is represented by U i denoted by ), n transmitting circuits connected one by one to n inverter circuits, wherein the transmitting circuit i includes a transmitting coil L i (The internal resistance is R i Indicates) and the primary series compensation capacitor C i , the current of the transmitting circuit i is I i The receiving end includes a receiving coil L s , Secondary side series compensation capacitor C s and the equivalent load resistance R L (Equivalent to rectifier, filter capacitor and load resistor), the system output AC current is I s Indicates. s =R s1 +R L is the total internal resistance of the receiving circuit (this part is Figure 1 No record, R s1 is the internal resistance of the receiving coil).

[0065] For the sake of Figure 1 The multi-transmitter wireless power transmission system shown realizes a simple, fast and accurate control of the transmission mode of targeted magnetic energy. The embodiment of the present invention provides a real eigenstate targeted magnetic energy control method based on multi-mutual inductance ratio front-end detection and positioning, which specifically includes the steps of:

[0066] S1, in the DC power supply U dc A voltage regulating circuit (using a buck-boost chopper circuit) is added between each inverter circuit. The circuit structure of the transmitting end of the multi-transmitter wireless power transmission system after adding the voltage regulating circuit is as follows: Figure 2 As shown;

[0067] S2, by controlling the corresponding voltage regulating circuit and inverter circuit, any two transmitting circuits are excited successively. When any transmitting circuit is excited, the remaining n-1 transmitting circuits that have not been excited and their inverter circuits form n-1 response circuits;

[0068] S3, measuring the currents of n-1 response loops corresponding to the two excitations, and calculating the mutual inductance ratios between the n transmitting coils and the receiving coils according to the measured currents;

[0069] S4, controlling the control signal ratio of n voltage regulating circuits to be the calculated mutual inductance ratio;

[0070] S5. Within the range of the starting frequency and the ending frequency, the excitation frequencies of the n inverter circuits are adjusted by increasing the set step size each time;

[0071] S6. Measure the phase difference of the input voltage and current of any transmitting circuit at each excitation frequency, and record the excitation frequencies from small to large with zero phase difference as the eigenfrequency f. 1 ,f 2 ,f 3 ;

[0072] S7, according to the system control requirements, the eigenfrequency f 1 or 2 or 3 The n inverter circuits are excited to perform wireless energy transmission for targeted magnetic energy control.

[0073] In step S1, the voltage regulating circuit is a buck-boost chopper circuit, wherein the voltage regulating circuit i includes a switch tube S i 、Inductance L bi 、Diode D i And filter capacitor C bi , i = 1, ..., n, the connection relationship is: switch tube S i The drain terminal is connected to the DC power supply U dc The positive terminal of the diode D iThe negative terminal and the inductor L bi One end of the gate is connected to the primary control circuit; the diode D i The positive terminal is connected to an input terminal of the inverter circuit i and a filter capacitor C bi One end of the inductor L bi The other end and filter capacitor C bi The other end is connected to the DC power supply U dc negative terminal.

[0074] When the transmitting coil adopts an orthogonal coil or a BP coil, the mutual inductance between the transmitting coils is not considered. According to the principle of the buck-boost chopper circuit and the full-bridge inverter, the DC voltage source U dc The relationship between the inverter AC output voltage fundamental effective value is shown in formula (1):

[0075]

[0076] Among them, δ i =t oni / t offi It is the ratio of the on-time and off-time of the switch tube of the voltage regulating circuit i.

[0077] According to the fundamental wave equivalence, the voltage regulating circuit and the inverter circuit can be equivalent to an AC voltage source. The equivalent circuit diagram of the system is as follows: Figure 3 As shown, where M is Indicates the transmitting coil L i With receiving coil L s When using transmitting coils with the same wire diameter and number of turns, the system parameters have the following relationship:

[0078]

[0079] according to Figure 3 The circuit shown in the figure is mathematically modeled and the loop voltage equation is written as follows:

[0080]

[0081] Among them, X = ωL-1 / ωC is the reactance of each transmitting circuit, X s =ωL s -1 / ωC s is the reactance of the receiving circuit.

[0082] As we all know, the magnetic energy generated by the coil depends on the current of the coil itself. According to formula (3), the relationship between the current between each transmitting coil and the current at the receiving end can be derived as follows:

[0083]

[0084] According to the above formula, the relationship between the current vector of each transmitting coil and the current vector of the receiving end is as follows: Figure 4 As shown, it is obvious that only when the current of the transmitting coil is in phase, the current of the receiving coil can reach the maximum, that is, the superposition of the magnetic energy of the receiving coil in this direction is the strongest, and the maximum energy transmission of the targeted magnetic energy is achieved. When the current of the transmitting coil is in phase, taking the transmitting loop 1 as a reference, it is assumed that the current amplitude of the transmitting loop 2, 3, ..., n and the current amplitude of the transmitting loop 1 are related to the current amplitude of the transmitting loop as follows:

[0085]

[0086] Adjust the compensation capacitance of the transmitting coil and the receiving coil to set the coil natural frequency of the transmitting circuit and the receiving circuit consistent. The self-inductance and compensation capacitance of the coil are shown in the following formula:

[0087]

[0088] However, the mutual inductance between the receiving coil and each transmitting coil often has a large difference. If only the current of each transmitting coil is in phase and the magnitude of the current amplitude is not considered, the system will have a large magnetic leakage and low system efficiency. The real eigenstate working mode can achieve the maximum power of the system while ensuring the transmission efficiency of the system, that is, to achieve the transmission of targeted magnetic energy.

[0089] According to the system characteristics of the real eigenstate working mode, the relationship between the currents of each transmitting coil in equation (5) is substituted into equations (3) and (4), and the voltage loop equation of the transmitting coil 1 is derived as shown below:

[0090]

[0091] According to formula (7), the input impedance of each transmitting circuit is calculated as follows:

[0092]

[0093] in:

[0094]

[0095] According to formula (9), if the voltage and current of each transmitting circuit are in phase, the system has two modes: fixed-frequency real eigenstate mode and floating-frequency real eigenstate mode. The parameter conditions are shown in the following formula:

[0096]

[0097] Formula (10) shows that the parameter condition of the fixed-frequency real eigenstate mode requires that the reactance of the transmitting circuit is equal to the reactance of the receiving circuit, that is, the eigenfrequency of the real eigenstate working mechanism is the inherent resonant frequency ω of the coil 0The parameter conditions of the floating frequency real eigenstate mode are related to the electrical parameters of the system and the current amplitude ratio.

[0098] According to the parameter conditions of the floating frequency mode in formula (10), since the mutual inductance of each transmitting coil is different, in order to make the reactance of each transmitting circuit zero, the excitation current and mutual inductance of each transmitting circuit should satisfy the following relationship:

[0099]

[0100] Formula (11) shows that the ratio of the mutual inductance to the current of each transmitting loop should be equal. Substituting formula (11) into (10), the relationship between the resonant frequency and the electrical parameters of the floating frequency mode is derived as follows:

[0101]

[0102] Due to the quality factor of the wireless power transfer system coil Generally, it is set very large. After discarding the negative solution of ω, the resonant frequency of the system is calculated as shown in the following formula:

[0103]

[0104] in:

[0105]

[0106] Therefore, the parameter conditions of the floating frequency mode can be further derived as the eigenfrequency ω 1,2 The constraints of the intrinsic frequency and the excitation current are related to the system electrical parameters. The current amplitude ratio constraint requires that the current amplitude ratio and mutual inductance ratio of each transmitting circuit are equal. The parameter conditions of the fixed frequency mode are only for the intrinsic frequency ω 0 A constraint is made, requiring the eigenfrequency ω 0 is the natural frequency of the coil, and there is no requirement for the excitation current of each transmitting circuit.

[0107] The difference in the excitation current of each transmitting circuit will cause the difference in the targeted magnetic energy, affecting the transmission efficiency of the system. In this example, the excitation current constraint condition that optimizes the efficiency is derived through the efficiency expression of the targeted magnetic energy wireless power transmission system. The general expression of the energy efficiency characteristics of the system is as follows:

[0108]

[0109] Substituting equations (3), (5) and (11) into equation (16), the efficiency expression of the system under the real eigenstate working mechanism is derived as follows:

[0110]

[0111] Formula (17) shows that the efficiency of the floating frequency mode is a certain value after the excitation current and the eigenfrequency are constrained, while the efficiency of the fixed frequency mode is related to the current amplitude ratio and the mutual inductance. By taking the partial derivative of the current amplitude ratio of each transmitting loop in the fixed frequency mode, the current amplitude ratio of each transmitting loop that makes the system efficiency optimal is calculated as shown in the following formula:

[0112]

[0113] According to formula (18), the current amplitude ratios of each transmitting loop are consistent and nested. Therefore, it is not difficult to obtain that the current amplitude ratios of each transmitting loop should also satisfy formula (11), that is, the ratio of the mutual inductance to the current of each transmitting loop is equal. Therefore, the excitation current constraints of the floating frequency mode and the fixed frequency mode of the real eigenstate working mechanism are the same.

[0114] Substituting equation (11) into equation (17), the system efficiency of the real eigenstate working mechanism is calculated as:

[0115]

[0116] in is the coupling coefficient between the i-th transmitting coil and the receiving coil.

[0117] Formula (19) shows that the transmission efficiency of the system in the fixed frequency mode is positively correlated with the square sum of the coupling coefficients, and the efficiency increases with the increase of the square sum of the coupling coefficients. However, the system efficiency in the floating frequency mode is only related to the electrical parameters of the system itself.

[0118] As for the output power characteristics of the real eigenstate working mechanism, substituting equation (11) into equation (8) to calculate the input impedance under the real eigenstate working mechanism is as follows:

[0119]

[0120] Substituting equation (11) into equation (20), the relationship between the excitation voltage and mutual inductance of each transmitting circuit can be calculated as follows:

[0121]

[0122] Where λ is the excitation coefficient.

[0123] Equation (21) shows that when voltage source excitation is used, the excitation current constraint of equation (11) can be converted into an excitation voltage constraint. Substituting equation (11) and equation (20) into the general expression of power shown below:

[0124]

[0125] The output power of the real eigenstate working mechanism system is calculated as follows:

[0126]

[0127] Equation (23) shows that when the excitation coefficients are the same, the output power of the fixed frequency mode is positively correlated with the sum of the squares of the coupling coefficients, while the output power of the floating frequency mode is proportional to the sum of the squares of the coupling coefficients.

[0128] In summary, the real eigenstate working mechanism is divided into fixed frequency mode and floating frequency mode. In terms of parameter conditions, the constraints of the excitation current in the fixed frequency mode and the floating frequency mode are the same, but the constraints of the eigenfrequency are different; in terms of energy efficiency characteristics, the efficiency and power of the fixed frequency mode are positively correlated with the square sum of the coupling coefficients, while the efficiency of the floating frequency mode is only related to the electrical parameters of the system itself, and the power is proportional to the square sum of the coupling coefficients.

[0129] According to the parameter conditions of the real eigenstate working mechanism, the excitation current constraints of the fixed frequency mode and the floating frequency mode both require that the ratio of each transmitting loop current to the mutual inductance is equal. Therefore, this example identifies the key parameter mutual inductance ratio. The mutual inductance ratio identification principle diagram is shown in Figure 1. Figure 5 As shown in the figure (when stimulating the transmitting circuit 1), the MCU applies a driving signal to control the switch tubes of the voltage regulating circuit and the inverter circuit. According to the fundamental wave equivalent principle, the voltage regulating circuit 1 and the inverter circuit 1 can be equivalent to an AC voltage source to form an excitation circuit; the inverter circuit 2, ..., n can be equivalent to a short circuit to form a response circuit. The equivalent circuit of multiple mutual inductance ratio identification is shown in Figure 6 The working state of the switch tubes of the inverter circuit 2,…,n is as follows Figure 7 As shown (taking inverter 2 as an example), (a) corresponds to the forward induced voltage, and (b) corresponds to the reverse induced voltage.

[0130] like Figure 7 As shown in (a), when the induced voltage jωM 2s I s When it is positive, the loop current flows through the body diode D 21 With switch S 23 The conduction forms a loop. Figure 7 As shown in (b), when the induced voltage jωM 2s I s When it is negative, the loop current flows through the body diode D 22 With S 21 The conduction forms a circuit.

[0131] according to Figure 6 The KVL equation for the response loop is as follows:

[0132]

[0133] According to formula (24), the excitation circuit generates a current I in each response circuit. 2 ,I3 ,…,I n The relationship with mutual inductance is as follows:

[0134] M 2s :…:M ns =I 2 :…:I n (25)

[0135] Formula (25) shows that the ratio of the mutual inductance to the current of each response loop is equal. Therefore, by detecting the ratio of the current of each response loop at the front end, the mutual inductance ratio of each response loop can be obtained.

[0136] As for the mutual inductance of the excitation circuit, the same principle is used, with the transmitting coil 2 as the excitation circuit and the transmitting coils 1, 3, 4, ..., n as the response circuit. The same method is used to measure the relationship between the response circuit current and the mutual inductance ratio as shown in the following formula:

[0137] M 1s :M 3s :…:M ns =I′ 1 :I′ 3 :…:I' n (26)

[0138] By combining equations (25) and (26), by measuring the current of the response loop twice, the mutual inductance of each transmitting loop and the current values ​​of the two measurements have the following relationship:

[0139] M 1s :M 2s :M 3s :…:M ns =I′ 1 I n :I 2 I′ n :I 3 I′ n :…:I n I′ n (27)

[0140] In summary, formula (27) shows that by controlling the switch tubes of the voltage regulating circuit and the inverter circuit through the MCU, the mutual inductance ratio can be calculated by only measuring the current of the response loop at the front end.

[0141] Take the example of driving circuit 1 and driving circuit 2 in sequence, refer to Figure 5 The schematic diagram and Figure 8 As shown in the flowchart, the multi-mutual inductance ratio detection process of steps S2 and S3 specifically includes the following steps:

[0142] A1, control the switch tube S of the voltage regulating circuit 1, ..., n 1 ,…,Sn , the control signal is δ 1 =1,δ 2 =…=δ n =0 (only voltage regulator circuit 1 works);

[0143] A2, control the switch tube of inverter circuit 1, with frequency The excitation inverter 1 is used to convert the inverter circuit 1 into an AC voltage source, and the transmitting circuit 1 is used as an excitation circuit;

[0144] A3, control the switch tubes of the inverter circuits 2, 3…, n, and only turn on the S of each inverter circuit. i1 ,S i3 The switch tube makes the inverter circuit 2, 3 ..., n equivalent to a short circuit, and the transmitting circuit 2, 3 ..., n is used as a response circuit;

[0145] A4, measure the current I of the response loop 2, 3…, n 2 ,I 3 ,…,I n ;

[0146] A5, control the switch tube S of the voltage regulating circuit 1, ..., n 1 ,…,S n , the control signal is δ 2 =1,δ 1 =δ 3 =…=δ n =0 (only voltage regulating circuit 2 works);

[0147] A6, control the switch tube of inverter circuit 2, with frequency Exciting inverter 2, the inverter circuit 2 is equivalent to an AC voltage source, and the transmitting circuit 2 is used as an excitation circuit;

[0148] A7, control the switch tubes of the inverter circuits 1, 3…, n, and only turn on the S of each inverter circuit. i1 ,S i3 The switch tube makes the inverter circuit 1, 3 ..., n equivalent to a short circuit, and the transmitting circuit 1, 3 ..., n is used as a response circuit;

[0149] A8. Measure the current I′ of the response loop 1, 3…, n 1 ,I′ 3 ,…,I′ n ;

[0150] A9. Calculate the mutual inductance ratio M based on the measured current value 1s :M 2s :M 3s :…:M ns =I′ 1 I n :I 2I′ n :I 3 I′ n :…:I n I′ n .

[0151] Based on the measured mutual inductance ratio, the two floating frequencies ω of the system need to be further determined. 1 and ω 2 , so as to control the excitation frequency of the inverter circuit according to different requirements. According to the parameter conditions of the real eigenstate working mechanism, the working frequency of the fixed frequency mode is the coil natural frequency ω 0 , the operating frequency of the floating frequency mode is the system resonant frequency ω 1,2 , and ω 1,2 It is related to the electrical parameters of the system. Therefore, in this case, the key parameter eigenfrequency needs to be identified. Fig. 9 The eigenfrequency identification schematic diagram and Fig.10 As shown in the intrinsic frequency identification flow chart, after the system identifies the mutual inductance ratio, the MCU applies the illustrated signal to control the switch tubes of the voltage regulator circuit and the inverter circuit. According to the fundamental wave equivalent principle, the voltage regulator circuit 1, ..., n and the inverter circuit 1, ..., n can be equivalent to an AC voltage source with adjustable voltage and frequency. The equivalent circuit of the intrinsic frequency identification is shown in Fig.11 As shown. 1 :…:U n =M 1s :…:M ns , adjust the ratio of the voltage to the mutual inductance of each transmitting circuit to be equal to meet the voltage excitation conditions.

[0152] Substituting equation (22) into equation (1), the relationship between the driving signal and the mutual inductance ratio of the voltage regulating circuit is calculated as follows:

[0153]

[0154] According to formula (12), the relationship between the eigenfrequencies can be deduced as follows:

[0155] ω 1 <ω 0 <ω 2 (29)

[0156] According to the system characteristics of the real eigenstate working mechanism, when the system works in the real eigenstate working mechanism, the input reactance of each transmitting circuit is zero, and the system presents zero phase angle. Based on this, the excitation frequency of each transmitting circuit is controlled by MCU, and the frequency scanning method is adopted to detect the phase angle between the input voltage and current of the front-end transmitting circuit to identify the eigenfrequency of the real eigenstate working mechanism.

[0157] More specifically, the eigenfrequency determination steps S4 to S6 are as follows: Fig. 9 and Process Fig.10 As shown, the specific steps include:

[0158] B1. Input the calculated mutual inductance ratio M between the transmitting coils 1s :…:M ns ;

[0159] B2. According to the mutual inductance ratio, control the switch tube S of the voltage regulating circuit 1, 2, ..., n 1 ,…,S n , the control signal is δ 1 :…:δ n =M 1s :…:M ns ;

[0160] B3, adjust the excitation frequency of the inverter circuit 1, 2, ..., n, and excite the system with 80kHz as the starting frequency;

[0161] B4. Measure the phase difference between the input voltage and current of the transmitting circuit 1;

[0162] B5. Judge the phase difference. If the phase difference is zero, record the excitation frequency at this time, from small to large, as f 1 ,f 2 ,f 3 ; If the phase difference is not zero, determine whether the excitation frequency reaches the termination frequency of 120kHz. If the excitation frequency has not reached the termination frequency, increase the excitation frequency by a step of 100Hz and return to step B4;

[0163] B6, output eigenfrequency f 1 ,f 2 ,f 3 .

[0164] Among the three eigenfrequencies, one is the coil natural frequency, that is, the inverter driving frequency corresponding to the fixed frequency mode, and the other two are floating frequencies, that is, the inverter driving frequencies corresponding to the floating frequency mode.

[0165] In summary, without changing the system structure, the voltage regulating circuit and the inverter circuit are controlled by the MCU, the phase of the input voltage and current is detected at the front end, and the intrinsic frequency can be identified through frequency scanning and phase detection.

[0166] For the above conclusions, this example uses MATLAB's SIMULINK circuit simulation software to identify the key parameters (mutual inductance ratio and eigenfrequency) of the real eigenstate working mechanism and the energy efficiency characteristics of the targeted magnetic energy. The simulation model takes three orthogonal coils with three-dimensional omnidirectional magnetic energy emission capability as an example, and the simulation structure diagram and simulation parameters of the system are shown in Table 1.

[0167] Table 1 Simulation parameter settings

[0168]

[0169] First, the identification of the mutual inductance ratio is verified, with M 1s :M 2s :M 3s =4:2:1 as an example, the transmitting circuit 1 is used as the excitation circuit, and the transmitting circuits 2 and 3 are used as the response circuits. The current of the response circuit is as follows Fig.12 shown.

[0170] according to Fig.12 It can be seen that the current I of the response circuit 2 =9.703,I 3 =4.852, we can calculate that the current ratio is equal to the mutual inductance ratio I 2 :I 3 =M 2s :M 3s =2:1, the simulation is consistent with the theory. Next, the transmitting loop 2 is used as the excitation loop, and the transmitting loops 1 and 3 are used as the response loops. The response loop current is as follows: Fig.13 As shown. Fig.13 It can be seen that the current I' of the response circuit 1 =9.599, I′ 3 =2.408, it can be calculated that the current ratio is equal to the mutual inductance ratio I' 1 :I′ 3 =M 1s :M 3s =3.986:1, the simulation is consistent with the theory. According to the measured current I 2 ,I 3 ,I′ 1 ,I′ 3 , calculate M 1s :M 2s :M 3s =I′ 1 I 3 :I 2 I′ 3 :I 3 I′ 3 =3.987:2:1, the simulation is consistent with the theory.

[0171] Next, the identification of the eigenfrequency is verified. Adjust the excitation voltage of each transmitting coil to U 1 :U 2 :U 3 =M 1s :M 2s :M 3s , and U 1=60V. By frequency scanning, measure the voltage and current phase difference of transmitting circuit 1. The conversion between angular frequency and frequency is f=ω / 2π. The excitation voltage of transmitting circuit 1 and current The curve of phase difference changing with frequency is as follows Fig.14 As shown. Fig.14 It can be seen that the frequencies are f 0 ,f 1 ,f 2 When the voltage and current are in phase, f 0 is the natural resonant frequency of the coil, f 1 ,f 2 is the resonant frequency of the system, and the simulation is consistent with the theory.

[0172] Finally, the energy efficiency characteristics of the real eigenstate working mechanism targeting magnetic energy are verified. The mutual inductance of each transmitting loop is set to M 1s =20μH,M 2s =10μH,M 3s =5μH, the voltage of transmitting circuit 1 is U 1 =20V, excitation coefficient λ=10 6 The relationship between the output power and transmission efficiency of the system under the real eigenstate working mechanism and the load change is as follows: Fig.15 , Fig.16 As shown. Fig.15 It can be seen that the power output level of the floating frequency mode is in the hundreds of watts, and the power output level of the fixed frequency mode is in the watts. As the load increases, the output power of the floating frequency mode decreases, while the fixed frequency mode is the opposite. Fig.16 It can be seen that the transmission efficiency of the fixed frequency mode is greater than that of the floating frequency mode, and the efficiency of both the fixed frequency mode and the floating frequency mode increases with the increase of the load.

[0173] When the load resistance is set to R L =15Ω, the voltage of transmitting circuit 1 is U 1 =20V. The relationship between the output power and transmission efficiency of the system under the real eigenstate working mechanism and the change of the square sum of the coupling coefficient is as follows: Fig.17 , Fig.18 As shown. Fig.17 It can be seen that the output power capacity of the floating frequency mode is greater than that of the fixed frequency mode. The output power of the floating frequency mode is proportional to the square sum of the coupling coefficients, and the power output level can reach the kilowatt level. The output power of the fixed frequency mode does not change much with the square sum of the coupling coefficients, and the power output level is always at the watt level. Fig.18 It can be seen that the transmission efficiency of the fixed frequency mode is greater than that of the floating frequency mode. The transmission efficiency of the fixed frequency mode increases with the increase of the square sum of the coupling coefficients, and the efficiency is always maintained at about 95%. The transmission efficiency of the floating frequency mode does not change with the square sum of the coupling coefficients, and the efficiency is always 88%.

[0174] Therefore, both the floating frequency mode and the fixed frequency mode under the real eigenstate working mechanism have higher transmission efficiency and greater power output capacity. However, the fixed frequency mode focuses on high-efficiency transmission of the system, while the floating frequency mode focuses on high power output.

[0175] When performing the magnetic energy targeted control in step S7, if high power output is required, the floating frequency drive is selected, and if high efficiency output is required, the fixed frequency drive is selected.

[0176] In summary, the simulation results are consistent with the theoretical derivation conclusions. By controlling the switch tube and detecting the current of the response loop, the identification method of multiple mutual inductance ratios was verified. And by voltage amplitude control and frequency scanning, the identification of eigenstate frequency was verified. Finally, the energy efficiency characteristics of the floating frequency mode and fixed frequency mode of the real eigenstate working mechanism were verified, and high-efficiency targeted magnetic energy transmission was achieved.

[0177] In summary, the real eigenstate targeted magnetic energy control method based on multi-mutual inductance ratio front-end detection and positioning provided by the present invention has the following advantages:

[0178] (1) Based on targeted magnetic energy wireless power transmission, the real eigenstate working mechanism under the multi-transmitting coil architecture is derived, the floating frequency mode and fixed frequency mode of the real eigenstate working mechanism are established, and the excitation current constraint conditions and eigenstate frequency constraint conditions are obtained;

[0179] (2) Aiming at the constraints of the excitation current, a method based on front-end identification of key parameters (multiple mutual inductance ratios) is proposed. The system structure and principle of identifying mutual inductance ratios are explained, and the mathematical relationship between the mutual inductance ratios and the current amplitudes of each response loop is constructed. The front-end identification of mutual inductance ratios is achieved only by controlling the switching tubes of the inverter circuit. Without changing the original circuit structure or introducing additional circuits, and without the need for communication between the primary and secondary sides, the mutual inductance ratios between any number of transmitting coils can be identified, which greatly simplifies and facilitates the identification of key parameters of targeted magnetic energy.

[0180] (3) Aiming at the eigenstate frequency constraint, a front-end identification method based on frequency scanning is proposed on the basis of mutual inductance ratio identification. According to the zero phase angle characteristic of the real eigenstate, the eigenstate frequency of the system is obtained. The eigenstate frequency identification method eliminates the complex calculation process of the floating frequency mode eigenfrequency. According to the zero phase angle characteristic, it directly detects the phase angle of the input impedance, which greatly reduces the difficulty of obtaining the eigenfrequency value.

[0181] (4) Targeted magnetic energy transmission: Through precise control of the excitation current, directional magnetic energy transmission is achieved, reducing the power and efficiency loss caused by magnetic energy leakage.

[0182] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A real eigenstate targeted magnetic energy control method based on multi-mutual inductance ratio front-end detection and positioning, characterized in that: Includes steps: S1, DC power supply U at the transmitting end of the multi-transmitter wireless power transmission system dc A voltage regulating circuit is added between each inverter circuit; the transmitting end of the multi-transmitter wireless power transmission system includes a DC power supply U dc and n identical inverter circuits connected in parallel therewith, and n identical transmitting circuits connected one-to-one with the n inverter circuits; S2, by controlling the corresponding voltage regulating circuit and inverter circuit, any two transmitting circuits are excited successively. When any transmitting circuit is excited, the remaining n-1 transmitting circuits that have not been excited and their inverter circuits form n-1 response circuits; S3, measuring the currents of n-1 response loops corresponding to the two excitations, and calculating the mutual inductance ratios between the n transmitting coils and the receiving coils according to the measured currents; S4, controlling the output voltage control signal ratio of n voltage regulating circuits to be the calculated mutual inductance ratio; S5. Within the range of the starting frequency and the ending frequency, the excitation frequencies of the n inverter circuits are adjusted by increasing the set step size each time; S6, measuring the phase difference of the input voltage and current of any transmitting circuit at each excitation frequency, and recording the excitation frequencies from small to large with zero phase difference as eigenfrequencies f1, f2, f3 in sequence; S7. According to the system control requirements, n inverter circuits are excited with the natural frequency f1, f2 or f3 to perform wireless energy transmission for targeted magnetic energy control.

2. The real eigenstate targeted magnetic energy control method based on multi-mutual inductance ratio front-end detection and positioning according to claim 1 is characterized in that: In step S3, the mutual inductance ratio between the n transmitting coils and the receiving coils is calculated based on the measured current as follows: The current ratio of the n-1 transmitting loops that are not excited during the first excitation is set equal to the mutual inductance ratio between the n-1 transmitting loops and the receiving coil, and a first mutual inductance ratio current ratio constraint relationship is established; The current ratio of the n-1 transmitting loops that are not excited during the second excitation is set equal to the mutual inductance ratio between the n-1 transmitting loops and the receiving coil, and a second mutual inductance ratio current ratio constraint relationship is established; The first mutual inductance ratio-current ratio constraint relationship and the second mutual inductance ratio-current ratio constraint relationship are combined to solve the mutual inductance ratio between the current n transmitting loops and the receiving coil.

3. The real eigenstate targeted magnetic energy control method based on multi-mutual inductance ratio front-end detection and positioning according to claim 2 is characterized in that: The step S7 is specifically as follows: If the system control requirement is high-efficiency transmission, n inverter circuits are excited by f2; If the system control requirement is high power transmission, n inverter circuits are excited by f1 or f3.

4. The real eigenstate targeted magnetic energy control method based on multi-mutual inductance ratio front-end detection and positioning according to claim 3 is characterized in that: In step S4, the voltage regulation circuit adopts a Buck-Boost step-up / step-down chopper circuit, and the control signal of the voltage regulation circuit i is defined as δ i =t oni / t offi , t oni ,t off are the on-time and off-time of the switch tube of the voltage regulating circuit i, i=1,2,,…,n.

5. The real eigenstate targeted magnetic energy control method based on multi-mutual inductance ratio front-end detection and positioning according to claim 4 is characterized in that: Steps S4 to S6 specifically include the following steps: B1. Input the calculated mutual inductance ratio M between each transmitting coil 1s :…:M ns , M is Indicates the transmitting coil L i With receiving coil L s mutual induction between B2. According to the mutual inductance ratio M 1s :…:M ns , control the switch tubes S1,…,S of the voltage regulating circuit 1,2,…,n n , the control signal is δ1:…:δ n =M 1s :…:M ns ; B3, adjusting the excitation frequency of the inverter circuits 1, 2, ..., n to excite the system at the starting frequency; B4. Measure the phase difference between the input voltage and current of any transmitting circuit; B5. Judge the phase difference. If the phase difference is zero, record the excitation frequency at this time, which is f1, f2, and f3 from small to large. If the phase difference is not zero, it is determined whether the excitation frequency reaches the termination frequency. If the excitation frequency has not reached the termination frequency, the excitation frequency is increased by a step size and the process returns to step B4. B6. Output eigenfrequencies f1, f2, f3.

6. The real eigenstate targeted magnetic energy control method based on multi-mutual inductance ratio front-end detection and positioning according to claim 5 is characterized in that: The transmitting circuit i includes a transmitting coil L i And the primary side series compensation capacitor C i .

7. The real eigenstate targeted magnetic energy control method based on multi-mutual inductance ratio front-end detection and positioning according to claim 6 is characterized in that: The receiving end of the multi-transmitter wireless power transmission system includes a receiving coil L s , Secondary side series compensation capacitor C s and the equivalent load resistance R L .

8. The real eigenstate targeted magnetic energy control method based on multi-mutual inductance ratio front-end detection and positioning according to any one of claims 1 to 7, characterized in that: In step S2, the excitation frequency for exciting any two transmitting loops is the natural frequency of the transmitting loop coils.

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